This invention relates generally to the hot rolling of rod and bar products, and is concerned in particular with the high speed rolling of close tolerance ferrous rod.
Over the last several decades, significant increases have been realized in the speeds at which ferrous rods are produced. For example, the mill delivery speed for 5.5 mm. rod has risen from about 40 m./sec. in the early 1960's to current speeds of 100 m./sec. Still higher speeds are now being proposed for future mills.
The credit for this advance is due in large part to the development of high speed finishing blocks of the type described in U.S. Pat. No. RE 28,107 (Wilson et al). These blocks employ small diameter cantilevered work rolls. The successive work roll pairs are mechanically tied to and driven by a common power source, and their axes are staggered by 90.degree. to provide twist-free rolling. The product is kept under very slight tension as it accelerates through the block.
The roll pairs are symmetrically adjustable to thereby provide a means of controlling the tolerance of the finished product. Such adjustments are usually required to compensate for variations in the temperature and tolerance of the product being fed to the finishing block. However, as finishing speeds continue to increase, it becomes more and more difficult to make needed roll parting adjustments in a timely manner and without upsetting the delicate tension relationship between successive roll passes in the finishing block.
The objective of the present invention is to provide a means of exercising much closer control over the tolerance of the product being fed to the finishing block, thereby making it possible to significantly reduce and perhaps largely eliminate the need for making roll parting adjustments in the finishing block.